An EB-3 EB-6 double neck is in Spinout.
http://www.poster.net/spinout/spinout-elvis-presley-9963590.jpgThere are a few pics of him with it, and I believe his is still hanging round Graceland. The King liked his basses.
I believe the EB6 ES body is rarer than the SG body, but for some reason you never have to look too hard to find one for sale, albeit at a fairly high price. The SG EB6 seems to be less prevalent, and I would say I see those as frequently at I see the EB0F. I played the one in the first Wheeler book, as well as another ES one that was in SF around 1994. The play a lot like an EB2 with a couple of extra strings. I played an SG EB6 in NYC in 1982 on 48th. It played a lot like my EB-0 but with a couple of extra strings. All three experiences made me realize I wanted one. At that time a banjo peg EB2 was trading hands in the $100-300 range, which made me realize I didn't want one that bad. Having played them was enough.
I recall from a Wheeler book that the EB2B and EB2C were both offered as optional stock finishes in 1961, along with the EB2N which had been an option for a few years. The black and natural were dropped as official options when the EB2 took a sabbatical in 62 and 63. I have seen what would appear to be legit factory finishes of natural well after. I would not be surprised at all to find a legit factory finished EB2 of whatever colors Gibson used in that period - black, white, blue, cardinal red, etc. But that one is a nice refin. Opaque refins make me worry on an EB2 though.